Note 3 - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Income		$ 30,435	$ 14,834	$ 39,996	$ 23,567
Divided by:
Weighted average common shares outstanding (in shares)		29,022	29,246	29,059	29,321
Weighted average common stock equivalents (in shares)		12	22	14	22
Total weighted average common shares outstanding and common stock equivalents (in shares)		29,034	29,268	29,073	29,343
Basic earnings per common share (in dollars per share)		$ 1.05	$ 0.51	$ 1.38	$ 0.80
Diluted earnings per common share (1) (in dollars per share)	[1]	$ 1.05	$ 0.51	$ 1.38	$ 0.80
Dividend payout ratio		16.20%	31.40%	24.60%	40.00%

[1] For the three and six months ended June 30, 2016 and 2015, there were no stock options that were anti-dilutive.